Final answer:
White blood cells are referred to as leukocytes, which are an essential component of the body's immune defense, protecting against pathogens and removing debris.
Step-by-step explanation:
White blood cells are also referred to as leukocytes. Within the circulatory system, white blood cells play a crucial role in the body's immune response. Leukocytes are involved in defending the body against both bacteria and viruses and can be classified as either granulocytes or agranulocytes. These cells are continuously created in the body, and their lifespans can range from a few hours or days to even years. The formed elements of the blood include three main types of cells: erythrocytes (red blood cells), leukocytes (white blood cells), and platelets (or thrombocytes). While erythrocytes are responsible for delivering oxygen to body cells and removing carbon dioxide, leukocytes protect against invading microorganisms and help in the clean-up of cellular debris.